A review of water electrolysis-based systems for hydrogen production using hybrid/solar/wind energy systems

Pt1.8Pd0.2CuGa Intermetallic Nanocatalysts with Enhanced Methanol Oxidation Performance for Efficient Hybrid Seawater Electrolysis

Seawater electrolysis is a potentially cost-effective approach to green hydrogen production, but it currently faces substantial challenges for its high energy consumption and the interference of chlorine evolution reaction (ClER). Replacing the energy-demanding oxygen evolution reaction with methanol oxidation reaction (MOR) represents a promising alternative, as MOR occurs at a significantly low anodic potential, which cannot only reduce the voltage needed for electrolysis but also completely circumvents ClER. To this end, developing high-performance MOR catalysts is a key. Herein, a novel quaternary Pt1.8Pd0.2CuGa/C intermetallic nanoparticle (i-NP) catalyst is reported, which shows a high mass activity (11.13 A mgPGM -1), a large specific activity (18.13 mA cmPGM -2), and outstanding stability toward alkaline MOR. Advanced characterization and density functional theory calculations reveal that the introduction of atomically distributed Pd in Pt2CuGa intermetallic markedly promotes the oxidation of key reaction intermediates by enriching electron concentration around Pt sites, resulting in weak adsorption of carbon-containing intermediates and favorable adsorption of synergistic OH- groups near Pd sites. MOR-assisted seawater electrolysis is demonstrated, which continuously operates under 1.23 V for 240 h in simulated seawater and 120 h in natural seawater without notable degradation.

Electrocatalysis in Solid Oxide Fuel Cells and Electrolyzers

Interest in energy-to-X and X-to-energy (where X represents green hydrogen, carbon-based fuels, or ammonia) technologies has expanded the field of electrochemical conversion and storage. Solid oxide electrochemical cells (SOCs) are among the most promising technologies for these processes. Their unmatched conversion efficiencies result from favorable thermodynamics and kinetics at elevated operating temperatures (400-900 °C). These solid-state electrochemical systems exhibit flexibility in reversible operation between fuel cell and electrolysis modes and can efficiently utilize a variety of fuels. However, electrocatalytic materials at SOC electrodes remain nonoptimal for facilitating reversible operation and fuel flexibility. In this Review, we explore the diverse range of electrocatalytic materials utilized in oxygen-ion-conducting SOCs (O-SOCs) and proton-conducting SOCs (H-SOCs). We examine their electrochemical activity as a function of composition and structure across different electrochemical reactions to highlight characteristics that lead to optimal catalytic performance. Catalyst deactivation mechanisms under different operating conditions are discussed to assess the bottlenecks in performance. We conclude by providing guidelines for evaluating the electrochemical performance of electrode catalysts in SOCs and for designing effective catalysts to achieve flexibility in fuel usage and mode of operation.

Green hydrogen: Paving the way for India's decarbonization revolution

The potential of green hydrogen to make India self-sufficient and energy-independent is reviewed in this study. We integrated technological advancements, economic analysis, and policy frameworks to provide a comprehensive overview of the green hydrogen landscape in India. This review examines cost reductions in electrolyzer technology, the potential for renewable energy integration, and the socio-economic benefits of green hydrogen adoption. Additionally, the study proposes innovative policy measures tailored to India's unique conditions, such as targeted subsidies and incentives for green hydrogen production and use. The research highlights significant cost reductions and increased renewable power generation as key factors contributing to the economic viability of green hydrogen in India. It underscores the importance of large-scale production and advancements in electrolyzer technology. Furthermore, the study emphasizes the necessity of clear regulatory frameworks, infrastructure development, and financing to support the deployment of a green hydrogen economy in India. By implementing a strategic roadmap for green hydrogen, India can reduce its reliance on fossil fuels, lower greenhouse gas emissions, and become a major player in the global green hydrogen market. The proposed policy measures and technological advancements are crucial for successfully adopting and deploying green hydrogen, ensuring energy self-sufficiency and long-term economic sustainability for India.

State-of-the-art review on hydrogen's production, storage, and potential as a future transportation fuel

Global energy consumption is expected to reach 911 BTU by the end of 2050 as a result of rapid urbanization and industrialization. Hydrogen is increasingly recognized as a clean and reliable energy vector for decarbonization and defossilization across various sectors. Projections indicate a significant rise in global demand for hydrogen, underscoring the need for sustainable production, efficient storage, and utilization. In this state-of-the-art review, we explore hydrogen production methods, compare their environmental impacts through life cycle analysis, delve into geological storage options, and discuss hydrogen's potential as a future transportation fuel. Combining electrolysis to make hydrogen and storing it in porous underground materials like salt caverns and geological reservoirs looks like a good way to balance out the variable supply of renewable energy and meet the demand at peak times. Hydrogen is a key component of our sustainable economy, and this article gives a broad overview of the process from production to consumption, touching on technical, economic, and environmental concerns along the way. We have made an attempt in this paper to compile different methods for the production of hydrogen and its storage, the challenges faced by current methods in the manufacturing of hydrogen gas, and the role of hydrogen in the future. This review paper will serve as a very good reference for hydrogen system engineering applications. The paper concludes with some suggestions for future research to help improve the technological efficiency of certain production methods, all with the goal of scaling up the hydrogen economy.

Review on Bubble Dynamics in Proton Exchange Membrane Water Electrolysis: Towards Optimal Green Hydrogen Yield

Water electrolysis using a proton exchange membrane (PEM) holds substantial promise to produce green hydrogen with zero carbon discharge. Although various techniques are available to produce hydrogen gas, the water electrolysis process tends to be more cost-effective with greater advantages for energy storage devices. However, one of the challenges associated with PEM water electrolysis is the accumulation of gas bubbles, which can impair cell performance and result in lower hydrogen output. Achieving an in-depth knowledge of bubble dynamics during electrolysis is essential for optimal cell performance. This review paper discusses bubble behaviors, measuring techniques, and other aspects of bubble dynamics in PEM water electrolysis. It also examines bubble behavior under different operating conditions, as well as the system geometry. The current review paper will further improve the understanding of bubble dynamics in PEM water electrolysis, facilitating more competent, inexpensive, and feasible green hydrogen production.

Financing the hydrogen industry: exploring demand and supply chain dynamics

The hydrogen industry has garnered substantial attention as a pivotal solution in addressing the intricate challenges of energy transition and achieving decarbonization across diverse sectors. The efficacy of deploying hydrogen technologies hinges upon the availability of robust financing mechanisms that can adequately support the dynamic demands and intricate supply chain intricacies inherent in the hydrogen sector. This comprehensive study is underpinned by a rigorous and systematic review of prior research on the hydrogen economy, leveraging authoritative databases including Web of Science, Scopus, and a range of consultancy-based reports. The study meticulously assesses the escalating interest in hydrogen as a paramount clean energy alternative, emphasizing its significance in propelling the multifaceted development and expansion of hydrogen supply chain dynamics. Furthermore, this research critically scrutinizes the intricate financial facets of the hydrogen sector, with a specific focus on delineating the drivers of demand and unraveling the complexities interwoven within the supply chain. Building upon this analysis, the study offers a forward-looking perspective on hydrogen financing, which considers emerging technologies, evolving policy landscapes, and dynamic market trends. In the face of existing global constraints within the hydrogen supply chain, innovative financing mechanisms such as green bonds, project financing underwritten by risk guarantees through public-private partnership paradigms, venture capital-equity models, and carbon pricing mechanisms emerge as indispensable tools poised to address these challenges effectively.

Decoupling the anodic and cathodic behavior in asymmetric electrochemical hydroiodic acid decomposition cell for hydrogen production in the iodine-sulfur thermochemical cycle

The HI section of the iodine-sulfur (I-S) thermochemical cycle for hydrogen production is one of the most energy-intensive sections and with significant material handling challenges, primarily due to the azeotrope formation and the corrosive nature of the hydroiodic acid-iodine-water mixture (HIx). As an alternative, the single-step direct electrochemical decomposition of the hydroiodic acid (HI) to generate hydrogen can circumvent the challenges associated with the conventional multistep HI section in the I-S cycle. In this work, we present new insights into the electrochemical HI decomposition process by deconvoluting the contributions from the anodic and the cathodic sections in the electrochemical cell system, specifically, the redox reactions involved and the overpotential contribution of the individual sections (anolyte and catholyte) in the overall performance. The studies on the redox reactions indicate that the HIx solution output from the Bunsen reaction section should be used as the anolyte. In contrast, aqueous HI without any iodine (I2) should be used as the catholyte. In the anodic section, the oxidation proceeds with I2 as the final oxidized species at low bias potentials. Higher positive potentials result in iodate formation along with oxygen evolution. For the catholyte section, I2 and tri-iodide ion reduction precede the hydrogen evolution reaction when I2 is present along with HI. Furthermore, the potential required for hydrogen production becomes more negative with an increasing I2/HI ratio in the catholyte. Polarization studies were conducted with simultaneous deconvolution of the anodic and cathodic behavior in a two-compartment cell. Model fitting of the polarization data revealed that the anolyte section's activation overpotential is negligibly low. In contrast, the activation overpotential requirement of the catholyte section is higher and dictates the onset of hydrogen production in the cell. Furthermore, the catholyte section dominates the total overpotential losses in the cell system. Operation in the ohmic resistance-dominated zone resulted in close to 90% current efficiency for the electrochemical HI decomposition. The results highlight that the potential for process improvement lies in reducing the ohmic resistance of the anolyte section and in lowering the activation overpotential of hydrogen evolution in the catholyte section.

The current status of hydrogen energy: an overview

Hydrogen is the most environmentally friendly and cleanest fuel that has the potential to supply most of the world's energy in the future, replacing the present fossil fuel-based energy infrastructure. Hydrogen is expected to solve the problem of energy shortages in the near future, especially in complex geographical areas (hills, arid plateaus, etc.) and harsh climates (desert, ice, etc.). Thus, in this report, we present a current status of achievable hydrogen fuel based on various scopes, including production methods, storage and transportation techniques, the global market, and the future outlook. Its objectives include analyzing the effectiveness of various hydrogen generation processes and their effects on the economy, society, and environment. These techniques are contrasted in terms of their effects on the environment, manufacturing costs, energy use, and energy efficiency. In addition, hydrogen energy market trends over the next decade are also discussed. According to numerous encouraging recent advancements in the field, this review offers an overview of hydrogen as the ideal renewable energy for the future society, its production methods, the most recent storage technologies, and transportation strategies, which suggest a potential breakthrough towards a hydrogen economy. All these changes show that this is really a profound revolution in the development process of human society and has been assessed as having the same significance as the previous industrial revolution.

Integration of geothermal-driven organic Rankine cycle with a proton exchange membrane electrolyzer for the production of green hydrogen and electricity

Engineers and scientists are increasingly interested in clean energy options to replace fossil fuels in response to rising environmental concerns and dwindling fossil fuel resources. There has been an increase in the installation of renewable energy resources, and at the same time, conventional energy conversion systems have improved in efficiency. In this paper, several multi-generation systems based on geothermal energy are modeled, assessed, and optimized which employ an organic Rankine cycle and a proton-exchange membrane electrolyzer subsystem in five different configurations. Based on the results, the evaporator mass flow rate and inlet temperature, turbine efficiency, and inlet temperature are the most influential parameters on system outputs, namely, net output work, hydrogen production, energy efficiency, and cost rate. In this study, the city of Zanjan (Iran) is selected for a case study, and the results of system energy efficiency for changes in ambient temperature are examined during the four seasons of the year. To determine the optimal values of the objective functions, energy efficiency, and cost rate, NSGA-II multi-objective genetic algorithm is employed, and a Pareto chart is derived. The system's irreversibility and performance are gauged by energy and exergy analyses. At the optimum state, the best configuration yields an energy efficiency and cost rate of 0.65% and 17.40 $/h, respectively.